JP2011107894A - Rfid system and anti-collision processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an RFID (radio frequency identification) system allowing complete prevention of collision of data, even in a state where a plurality of RFID tags overlap, and allowing instantaneous and accurate reading of the data of each RFID tag. <P>SOLUTION: In the RFID system, a modulation signal comprising a specific frequency is connected to a UID of the RFID tag 1, and a UID-equipped modulation signal is set. The plurality of RFID tags 1 each being provided with recording the UID-equipped modulation signal. A storage device 4 storing the UID-equipped modulation signal of each RFID tag 1 is provided, and a controller 5 performing poling so as to confirm the RFID tag 1 operating inside a loop antenna 3 and reading the UID from the UID-equipped modulation signal of the RFID tag 1 is provided. A modulation module 6, confirming a frequency of the modulation signal from the UID-equipped modulation signal of the RFID tag 1 whose operation is confirmed, is set. A transmitter 7 transmitting the signal of the confirmed frequency is provided. Information of each RFID tag 1, induced electromagnetically by the signal transmitted by the transmitter 7, is read by a reader/writer 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an RFID system and an anti-collision method for reading identification information unique to an RFID tag in a non-contact manner, and an RFID system and an anti-collision processing method for preventing data collision when individually reading the identification information of each RFID tag. About.

  RFID (Radio Frequency IDentification) is a generic term for a recognition method in which data is recorded or read using radio waves on a card-like or tag-like medium and communication is performed via an antenna. An RFID system using this RFID is a device that reads information of an RFID tag that records a unique identification number, data, and the like with an RFID reader.

  The RFID tag includes a semiconductor chip on which a memory is mounted and an antenna. Information such as a unique identification number and data is recorded in the memory of the semiconductor chip. This RFID tag includes an active tag with a built-in battery and a passive type that supplies power to the RFID tag using electromagnetic induction or microwaves from an RFID reader.

  The RFID reader includes a semiconductor chip that performs communication processing, an antenna, a port for connecting to a device such as a computer, and the like. The apparatus reads information from the memory in the RFID tag or writes information to the memory in the RFID tag by transmitting a command from the RFID reader to the RFID tag in accordance with a computer command.

  In addition, the RFID system uses different power supply methods for the RFID tag depending on the radio frequency band. As frequency bands used in RFID, there are 125 k to 135 kHz band, 13.56 MHz band, 2.45 GHz band, 860 M to 960 MHz band (UHF band), and the like. Among them, particularly in the 13.56 MHz band, a passive type RFID tag using electromagnetic induction can be used, and a management system using a large number of RFID tags is currently most frequently used.

  In a passive type RFID tag, when a plurality of RFID tags respond simultaneously when reading information from the RFID tag, a so-called data collision may occur, and the individual information may not be correctly recognized by the RFID reader. A mechanism for avoiding this is called anti-collision (collision prevention). For example, an ALOHA type anti-collision processing method generally used in a 13.56 MHz band RFID system or the like is as follows.

  First, the RFID reader designates a specific bit (about 1 to 4 bits) in the memory of the RFID tag as a time slot. Then, the RFID tag shifts the response timing according to the data of the time slot. For example, when using a 2-bit time slot, the four types of data “00, 01, 10, 11” are responded to the reader at different timings. When only one RFID tag responds simultaneously at each timing, the data of the RFID tag can be normally received. The RFID reader transmits to the RFID tag a command (Sleep / Mute) for setting a sleep state that does not respond for a certain time. On the other hand, when a plurality of tags respond simultaneously at each timing, a collision (collision) is detected. In this case, the process of responding to the reader at different timings is repeated for each of the four types of data “00, 01, 10, 11” using another two bits in the memory as a time slot. After all RFID tags have been read without causing a collision, the RFID reader finally transmits a command (Wake Up) for returning the RFID tag from the sleep state, and the series of processing ends.

  As described above, in the conventional anti-collision processing method, the time slot is changed many times until the number of tags that can be read simultaneously becomes one, and the search is repeated many times. Therefore, when reading a plurality of RFID tags, all tags are read. Inconvenience that it takes a long time to read, and when the number of RFID tags read at a time increases, the time required for reading further increases.

  Various processing methods and apparatuses for improving the anti-collision processing efficiency have been proposed (Patent Documents 1 to 3).

  The anti-collision processing method in Patent Document 1 allocates a partial area of UID information held by each wireless tag device as a Sub-ID region. The reading device (RFID reader) is a wireless tag device (RFID tag). ) Broadcast request transmission of the read request information, and each wireless tag device that has received the request returns its own Sub-ID information. The reading device performs anti-collision using the Sub-ID information transmitted from each wireless tag device, and specifies the Sub-ID information related to the acquired UID information as “xxx”. Then, the reading device acquires the remaining UID information (the portion of the UID information other than the Sub-ID information) whose Sub-ID information is “xxx” from the wireless tag device, and reconstructs the UID information. That's it.

  In Patent Document 2, an anti-collision function is mounted on an RFID tag, and a switching circuit for switching on and off the resonance capacitor is provided. As a result, if a certain level of power supply voltage / operating voltage on the RFID tag side is obtained, the identification of each RFID tag can be performed by the anti-collision function, so that the resonance frequency change is relatively rough. Even if it is set, stable operation can be secured.

  Further, Patent Document 3 intends to provide a wireless communication apparatus that can reduce the calculation load required for determining the number of assigned slots. In other words, in the conventional anti-collision, every time a time slot is assigned to each RFID tag, a predetermined probability calculation is performed to determine a new number of assigned slots. Therefore, a complicated probability calculation is repeated many times at high speed. There was a demand for high processing power that can be accommodated. Therefore, in Patent Document 3, for each type of assignable number of slots, an unread response device that transmits the number of slots and the next largest number of slots, including the identification information in one slot, is provided. A corresponding data storage unit that stores the number of unread response devices when the probability of being equal to one is equal, and a real number of the unread response device before the signal is transmitted and an unread data stored in the corresponding data storage unit The number of unread response devices is compared with the number of response devices, the smallest number of unread response devices larger than the real number is selected, and the number of slots corresponding to the number of unread response devices is read. A wireless communication device capable of reducing a calculation load required for determining the number of assigned slots. It is obtained by trying to provide.

JP 2006-148522 A Japanese Patent No. 3614157 Japanese Patent No. 4256894

  However, each of the anti-collision processing methods and apparatuses described in Patent Documents 1 to 3 executes the anti-collision processing until data of a plurality of RFID tags does not collide. In other words, data collision means that each RFID tag resonates when a radio signal of a specific frequency is transmitted from an RFID reader. Therefore, a group coupling phenomenon (for example, one RFID tag in a state where two RFID tags overlap each other) A phenomenon in which it cannot be determined as accurate data. The processing methods and apparatuses described in Patent Documents 1 to 3 are methods that repeatedly perform anti-collision processing until there is no RFID tag that cannot be determined due to data collision.

  As a result, in the conventional anti-collision processing method, it takes time to repeat the anti-collision processing until information is read from all RFID tags. For example, when a plurality of RFID tags are physically overlapped, all RFID tags The tag information could not be read instantly. Moreover, even if the information of all RFID tags can be read by repeating the anti-collision process, many problems remain in practical operation such as error information being included. For example, when a plurality of RFID tags are overlapped, a phenomenon called so-called solid coupling occurs in which information of the RFID tags is combined and one of the information is erased. It was extremely difficult. Therefore, it is desired to provide an RFID system and an anti-collision processing method that can instantaneously and accurately read RFID tag information without collision of data even when a plurality of RFID tags overlap.

  Accordingly, the present invention solves the above-described problems, completely prevents data collision even when a plurality of RFID tags are overlapped, and enables an RFID system and an anti-virus that can instantaneously and accurately read data of each RFID tag. The object is to provide a collision processing method.

  In order to achieve the above object, the first means in the present invention is an RFID system that recognizes information of the RFID tag 1 arranged in the loop antenna 3 in a contactless manner by a radio signal transmitted from the reader / writer 2. A modulation signal having a specific frequency + n is connected to the UID of the RFID tag 1 to form a modulation signal with UID, and a plurality of RFID tags 1 recording the modulation signal with UID, and the modulation signal with UID of each RFID tag 1 , The control device 5 that reads the UID of the RFID tag 1 by polling to confirm the RFID tag 1 that operates in the loop antenna 3, and the modulation with the UID of the RFID tag 1 that has been confirmed to operate. A modulation module 6 for selecting the frequency of the modulation signal from the signals, and a transmitter 7 for transmitting a signal of the frequency selected by the modulation module 6; The provided, certain information of each RFID tag 1 which is electromagnetically induced in the signal transmitted by the transmitter 7 to the RFID system read by a reader-writer 2.

  The second means sets the radio signal transmitted from the reader / writer to the 13.56 MHz band, and the modulation signal to be recorded on the RFID tag is 13.56 + n (n = 0.001 to 0) at the end of the UID of each RFID tag. .007 MHz) is set by concatenating modulation signals.

  The third means is an RFID system anti-collision processing method for recognizing information of the RFID tag 1 disposed in the loop antenna 3 in a non-contact manner using a radio signal transmitted from the reader / writer 2. Means for connecting a modulation signal having a specific frequency + n to set a modulation signal with UID and recording the modulation signal with UID on the RFID tag 1, and among a plurality of RFID tags 1 on which the modulation signal with UID is recorded To read the UID from the modulated signal with UID of each RFID tag 1 in order to confirm the RFID tag 1 operating in the loop antenna 3, and to modulate from the modulated signal with UID of the RFID tag 1 whose operation has been confirmed Means for selecting a frequency of the signal and transmitting a signal of the selected frequency, and each RFID tag 1 using the modulated signal with UID. In the anti-collision processing method of reading information in a reader-writer 2.

  In the fourth means, the radio signal transmitted by the reader / writer 2 is set to 13.56 MHz band, and the modulation signal is 13.56 + n (n = 0.001 to 0.007 MHz) at the end of the UID of each RFID tag 1. A means for solving the problem is that a modulation signal consisting of

  With the RFID system and anti-collision processing method of the present invention, the information of each RFID tag 1 can be read by individual modulation signals. As a result, there is no conventional data collision, and the data of each RFID tag can be read accurately.

  Moreover, unlike the conventional RFID system and anti-collision processing method, unlike the method in which anti-collision processing is repeated until there is no RFID tag that cannot be determined after data collision, data collision does not occur from the beginning. The tag data can be read instantaneously and accurately. Therefore, for example, when reading information on RFID tags attached to products in a supermarket or the like with a cash register, it is possible to read a large number of products in a shopping cart in a batch. High use became possible.

  Further, the radio signal transmitted from the reader / writer 2 is set to 13.56 MHz band, and the modulation signal is connected to the modulation signal composed of 13.56 + n (n = 0.001 to 0.007) at the end of the UID of the RFID tag 1. Thus, it is possible to use it for each of the most commonly used systems, and there is an advantage that it is extremely versatile.

1 is a schematic diagram illustrating one embodiment of a system of the present invention. It is a flowchart which shows the anti-collision processing method of this invention. It is a conceptual diagram which shows the setting state of the modulation signal with UID of this invention. It is a conceptual diagram which shows the setting condition of the modulation signal of this invention.

  According to the present invention, the original purpose of completely preventing data collision even when a plurality of RFID tags are overlapped and reading data of each RFID tag instantaneously and accurately is achieved.

  The present invention is an RFID system in which information of each RFID tag 1 electromagnetically induced by a signal transmitted by a transmitter 7 is read by a reader / writer 2. The RFID tag 1, the reader / writer 2, a loop antenna 3, and a storage device 4. The control device 5 is a main component (see FIG. 1).

  The RFID tag 1 uses a passive type that supplies power to the RFID tag 1 using electromagnetic induction from the reader / writer 2. Further, the RFID tag 1 is provided with an antenna coil for electromagnetic induction, and a read / write tag on which a memory of several tens of bytes to several tens of kilobytes is mounted and can be written many times is used. The radio frequency band used in the system of the present invention is currently most widely used and uses the 13.56 MHz band.

  The reader / writer 2 is a device for reading or writing an ID or the like from the memory in the RFID tag 1. The reader / writer 2 is composed of a semiconductor chip that performs communication processing, an antenna 2A for communicating through radio waves, and a port (serial, USB, wireless LAN, etc.) for connecting to a host system such as a PC. The When a command is wirelessly transmitted from the reader / writer 2 to the RFID tag 1 via the antenna 3A, data (such as a UID) can be read or written to the memory in the RFID tag 1.

  The loop antenna 3 becomes a radio field in which electromagnetic induction is generated by the radio signal of the reader / writer 2. When the RFID tag 1 enters the loop antenna 3, power is automatically supplied to the RFID tag 1. Is.

  The storage device 4 stores the modulation signal with UID recorded in each RFID tag 1 (see FIG. 3). This modulated signal with UID is set by connecting a UID of the tag 1 with a modulated signal having a specific frequency + n. The storage device 4 stores these UID-added modulation signals and data recorded in the memory in the RFID tag 1.

  The modulation signal with UID is a combination of a modulation signal obtained by further subdividing the 13.56 MHz band used by the system of the present invention and a UID preset in the RFID tag 1. This modulated signal is subdivided at 13.56 + n (n = 0.001 to 0.007 MHz). That is, when the baseband signal is 13.56 MHz, a modulated signal (13.561 MHz, 13.562 MHz, 13.563 MHz, 13.564 MHz, 13 is set by combining a baseband signal by setting a carrier wave in units of 0.001 MHz. .565 MHz and 13.567 MHz) (see FIG. 4). These subdivided modulation signals are connected and set at the end of the UID of the RFID tag 1 (see FIG. 3). At this time, the setting of n = 0.001 to 0.007 MHz is based on a range where stable operation can be confirmed by experiments.

  The control device 5 collates the UID data of the RFID tag 1 received by the reader / writer 2 with the storage device 4 and executes a specific operation. By repeating these procedures, data communication is performed between the reader / writer 2 and the RFID tag 1. Further, the present invention has an important function of polling to read the RFID tag 1 operating in the loop antenna 3 and reading the UID from the modulation signal with UID of the RFID tag 1.

  That is, the RFID tag 1 to which power is automatically supplied in the loop antenna 3 is confirmed by this polling. And the control apparatus 5 reads UID from the modulation signal with UID of the RFID tag 1 of an operation state, and confirms the modulation signal connected to this UID.

  The modulation module 6 confirms the frequency of the modulation signal from the modulation signal with UID of the RFID tag 1 whose operation has been confirmed, and modulates the 13.56 MHz signal into a subdivided signal. It has a function of transmitting a modulation signal.

  In order to read the UID of the RFID tag 1 in the system of the present invention, the reader / writer 2 first polls the RFID tag 1 in the loop antenna 3 from the control device 5 and confirms the UID of the RFID tag 1 that operates. The modulation module 6 selects a modulation signal from the modulation signal with UID recorded in the confirmed RFID tag 1 and transmits the modulation signal of each RFID tag 1 through the transmitter 7. When a command is transmitted to the RFID tag 1 on this modulated signal, the tag interprets the command and transmits its own UID data to the reader / writer 2 as a radio signal. The reader / writer 2 receives the UID data and transmits it to the control device 5. The control device 5 collates the UID data with the storage device 4 and executes a specific operation. By repeating such a procedure, data communication is performed between the reader / writer 2 and the RFID tag 1.

  In the system of the present invention, the following anti-collision processing method is employed (see FIG. 2).

  Step 1 is means for recording a modulation signal with UID in the RFID tag 1 by the control device 5 and the reader / writer 2. In this means, a modulation signal having a specific frequency + n is connected to the UID of the RFID tag 1 to set a modulation signal with UID, the modulation signal with UID is recorded in the RFID tag 1, and the UID is also stored in the storage device 4. The attached modulation signal is stored.

  Step 2 is a polling unit for the RFID tag 1. This polling is performed in order to confirm the RFID tag 1 that operates in the loop antenna 3 among the plurality of RFID tags 1 that record the modulation signal with UID. The UID of each RFID tag 1 whose operation has been confirmed by this polling is read.

  Step 3 selects the frequency of the modulation signal from the modulation signal with UID of the RFID tag 1 whose operation has been confirmed by the transmitter 7, transmits the signal of the frequency, and reads the information of the RFID tag 1 with the reader / writer 2. Means.

  Through these steps, when the information of each RFID tag 1 is read by the reader / writer 2 using the modulation signal with UID, even if a plurality of RFID tags are arranged in a stacked state, the data does not collide, and the information of the RFID tag Can be read instantaneously and accurately.

  The system of the present invention can be used in other radio frequency bands, and an active tag incorporating a battery can be used as the RFID tag 1. Furthermore, the configuration of the present invention is not limited to the illustrated example, and the design can be freely changed without changing the gist of the present invention.

1 RFID Tag 2 Reader / Writer 2A Antenna 3 Loop Antenna 4 Storage Device 5 Control Device 6 Modulation Module 7 Transmitter

Claims (4)

  In an RFID system that recognizes the information of an RFID tag placed in a loop antenna in a non-contact manner using a radio signal transmitted from a reader / writer, a modulation signal consisting of a specific frequency + n is connected to the UID of the RFID tag to attach a UID. Polling to confirm a plurality of RFID tags that form modulation signals and record the modulation signals with UID, storage devices that store the modulation signals with UID of each RFID tag, and RFID tags that operate within the loop antenna A control device for reading the UID of the RFID tag, a modulation module for confirming the frequency of the modulation signal from the modulated signal with UID of the RFID tag whose operation has been confirmed, and a signal of the frequency confirmed by the modulation module A transmitter, and information on each RFID tag electromagnetically induced by the signal transmitted by the transmitter RFID system characterized by reading a plate.   The radio signal transmitted by the reader / writer is set to 13.56 MHz band, and the modulation signal recorded in the RFID tag is a modulation consisting of 13.56 + n (n = 0.001 to 0.007 MHz) at the end of the UID of each RFID tag. The RFID system according to claim 1, wherein the RFID system is set by connecting signals.   In an anti-collision processing method of an RFID system that recognizes information of an RFID tag disposed in a loop antenna in a non-contact manner using a radio signal transmitted by a reader / writer, a modulation signal having a specific frequency + n is applied to the UID of the RFID tag. A means for connecting and setting a modulation signal with UID and recording the modulation signal with UID on the RFID tag, and an RFID tag operating in the loop antenna among the plurality of RFID tags having the modulation signal with UID recorded. Means for polling and reading the UID from the modulation signal with UID of each RFID tag, means for checking the frequency of the modulation signal from the modulation signal with UID of the RFID tag whose operation has been confirmed, and transmitting the signal of the frequency, And reading the information of each RFID tag with a reader / writer using the modulated signal with UID. Anti-collision processing method of the RFID system.   The radio signal transmitted by the reader / writer is set to 13.56 MHz band, and the modulation signal is obtained by connecting a modulation signal composed of 13.56 + n (n = 0.001 to 0.007 MHz) at the end of the UID of each RFID tag. The anti-collision processing method according to claim 3 set.

Images